Method and apparatus for making filters



March 8, 1966 Q sc u ETAL 3,238,852

METHOD AND APPARATUS FOR MAKING FILTERS Original Filed Oct. 5, 1954 2Sheets-Sheet 2 KXXXRX K XXXXXX XXXXXKX INVENTORS: MILTON O. SCHUR JAMESC. RICKARDS A TTORNE! United States Patent 3,238,852 METHOD ANDAPPARATUS FOR MAKING FILTERS Milton Oscar Schur, Asheville, and James C.Richards, Brevard, N.C., assignors, by mesnc assignments, to OlinMathieson Chemical Corporation, a corporation of Virginia Originalapplication Oct. 5, I954, Ser. No. 450,355. Divided and this applicationJune 2, 1965, Ser. No. 477,991

Claims. (Cl. 93-1) This application is a division of co-pendingapplication Serial No. 460,355, filed October 5, 1954.

This invention relates generally to smoking devices and moreparticularly to a method and apparatus for making filters for suchdevices and to an improved filter for tobacco smoke.

It has been proposed heretofore to provide cigarettes and other smokingdevices with a filter for the tobacco smoke. It has also been proposedto manufacture such filters by passing a continuous web of crepe paperor other compressible material into a forming cone which laterallygathers and compresses the web into cylindrical form having draftpassages therethrough, for example, as described by Davidson in US.Patent 2,164,702, issued July 4, 1939. Although such a process has manyadvantages over other methods for making tobacco smoke filters, it hasnot been entirely suitable, especially in the manufacture of filtershaving resistance to the fiow of smoke appreciably greater than that ofan equal length of the rod of tobacco comprising the cigarette proper,because the gathered and compressed web of material is difficult toenclose within a suitable wrapper at high speed production. It has beenfound that the compressed web exerts an internal pressure against thewrapper sufliciently high so that consequently it is very difficult toseal the overlapping edges of the wrapper at economic rates ofproduction. As a result, a larger percentage of the product may havepoorly sealed Wrappers or may be too variable in circumference. Poorlysealed or oversized rods cannot be utilized successfully in the machinewhich encloses the filter tip and tobacco within a Wrapper to form acigarette because of frequent jamming of the machine; and variablecircumference of the filter tip gives trouble in the production ofuniform filter-tipped cigarettes.

These disadvantages are partially overcome if prior to the formation ofthe filter rods the paper web is slit in the manner disclosed byDavidson in the aforesaid patent, but the slitting of the paper intoribbons in accordance with the method disclosed by Davidson introduces anumber of serious production problems. For instance, it is verydifficult, if not impossible, satisfactorily to enclose a plurality ofsuch smooth edged ribbons within a wrapper at high speeds without theoccasional breaking of strands between the slitters and forming tube.Further, the slitters require frequent and close attention, for shouldonly one of the numerous cutters required become dull or nicked, thepaper may tear and cause serious trouble.

It is an object of this invention to provide an apparatus and method formaking filters for smoking devices which are devoid of the foregoingdisadvantages. Another object of the invention is to provide anapparatus and method for making a more efficient filter than theheretofore available filter formed from a single continuous web or thefilter from a plurality of ribbons of compressible filter material.Still another object of the invention is to provide a more effectivefilter for cigarettes than heretofore known filters formed fromcompressible material.

Other objects will become apparent from the follow- Patented Mar. 1966ing description with reference to the accompanying drawing in which:

FIGURE 1 is a diagrammatical perspective view illustrating an embodimentof this invention;

FIGURES 2 and 3 are illustrations of typical superimposed rolls suitable'for use in the embodiment of FIG- URE 1;

FIGURE 4 is a fragmentary enlarged view showing the relative position ofthe web and the contacting surfaces of the rolls of FIGURE 2;

FIGURE 5 is an enlarged view of the surface of one of the rolls inFIGURE 3;

FIGURE 6 is a fragmentary sectional view taken along line CC of FIGURE5;

FIGURE 7 is a fragmentary view of a web of compressible materialstretched laterally to illustrate to best advantage the effect oftreating a web of paper with rolls illustrated in FIGURE 2;

FIGURE 8 is an enlarged View of that portion of FIG- URE 1 lying betweenthe lines A-A and BB;

FIGURE 9 is a fragmentary view of a web of compressible material aftercompression between rolls of the type illustrated in FIGURE 3;

And FIGURE 10 is a partially sectioned perspective view of a cigaretehaving a filter embodying the present invention.

Generally speaking, the foregoing objects as well as others areaccomplished in accordance with this invention by longitudinally feedinga web or strip of compressible material of substantially indefinitelength, tearing the web into ragged edged shreds, thereafter laterallygathering and compressing the web into a rod and subdividing the rodinto lengths. It is prefered to loosen the fibers of the compressiblematerial by embossing and to thereafter form discontinuous relativelyclosely spaced longitudinal rents therein throughout the length in orderto produce a web most suitable for laterally gathering and compressinginto cylindrical form.

It has been found in accordance with this invention that in filter rodsof a given draw or resistance to flow of smoke the internal pressure ofthe gathered and compressed material having the rents therein is muchless than when an untorn web of similar material is used and that thetorn web can be successfully enclosed Within a suitable wrapper withoutthe serious production difificulties caused by the overlapping edges ofthe wrapper not being tenaciously bound together when the rod-makingmachine is run at commercial speeds. Consequently, the filter rodsformed in accordance with this invention can be assembled with tobaccowithin a wrapper to form cigarettes on conventional cigarette makingmachines with less difficulty and expense than filter rods formed from asingle untorn web of compressible material enclosed within a Wrapperhaving unbound overlapping edges. Moreover, it has been found that lessof the compressible material is required to form an effective filter ifthe web thereof has been torn or pulled apart prior to the gathering andcompressing steps. Furthermore, such a filter of increased effectivenessrequires less of the compressible material to impose a given resistanceto the flow of smoke through the filter than would be required to imposea similar resistance if untorn compressible material was utilized. Thisis an advantage in the manufacture of filters because it enables theproduction of filters from less of the compressible material and thus ata reduced cost. The torn web because of the ragged, fuzzy edges of thetorn portions does not present the problem involved in Wrapping aplurality of smooth edged ribbons, for there is a tendency for theopposing ragged edges of the shreds to intermesh and to hold theplurality of shreds together into what is essentially a single web.

Referring to FIGURE 1 of the drawing a continuous Web of paper 1weighing about 21 grams per square meter is passed between pairs ofsuperimposed embossing rolls 2 and 3, and 4 and 5. In this particularembodiment, roll 2 is a positive roll and roll 3 is a negative rollforcing web 1 against the roughened surface of roll 2. Roll 5 is also apositive roll while roll 4 is a smooth surface roll like roll 3 urgingweb 1 against the roughened surface of roll 5. The resulting embossedweb of paper 1 is next passed between soft rubber roll 6 and steel roll7. In this particular embodiment shown in more detail in FIGURE 2, roll6 is made from sponge rubber having a Shore hardness from about 17 toabout 20. Roll 7 is a steel roll having a plurality of circumferentialgrooves 8 and ridges 9. As web 1 passes between these rolls, sufiicientpressure is maintained to urge the soft surface of roll 6 into thegrooves of roll 7. Web 1 is thus forced into grooves 8 of roll 7 asillustrated in FIGURE 4. Since the paper 1 is pinched in the nip betweenthe ridges 9 and the surface of rubber roll 6, paper 1 can not movelaterally. Consequently, paper 1 is stretched laterally and the fibersare pulled apart. It is essential in accordance with this invention thatsufficient pressure be applied to rolls 6 and 7 to pull apart the fibersof paper 1 and form rents 10 in paper 1 as illustrated to best advantagein FIGURES 7 and 8. The pressure on rolls 6 and 7 may be such as to formcontinuous rents 10 or it may be adjusted to form a plurality ofdiscontinuous rents 10 in web 1, but in order to facilitate handling ofthe web, it is preferred to adjust the apparatus to form discontinuousrents. In this particular embodiment, a fluid pressure of from about 54to 63 pounds per nip inch provided by compressed air is suflicient toform discontinuous rents in web 1 such as is indicated by the numeral10,

As illustrated in FIGURE 1, web 1 is moistened by means of a water spraybefore it is laterally gathered and compressed. This water spray may beapplied to the web by any suitable means such as for example, by meansof a suitable pump and an atomizer 12. Web 1 is laterally gathered andcompressed by means of the forming cone 30 such as utilized on cigarettemaking machines. Paper wrapper 13 is wound about the gathered andcompressed web 1 in cone 30 and the overlapping edges thereof are boundtogether by applying adhesive to edge 14 of wrapper 13 by means ofapplicator 15 and thereafter folding edge 14 into contact with theoverlapping portion of wrapper 13 by means of cylindrical member 16. Theoverlapping edges of wrapper 13 are tightly bound together by heatedroller 17 which removes liquid and sets the adhesive. The resulting rod18 is cut into individual lengths by rotary cutter 19.

Superimposed rolls 20 and 21 may be substituted for rolls 6 and 7 in theembodiment shown in FIGURE 1. These rolls are forced together undersufficient pressure to force the teeth 22 of roll 21 through paper 1 toform a plurality of rents 23 therein of the general type illustrated inFIGURE 9. In the embodiment of this type of roll shown in FIGURES 3, 5and 6, the teeth are frusto-conical shaped but teeth of other shapeshaving a dull point such that the paper is torn and not out can beutilized. For example, the point of the teeth may be substantiallyspherical. It is also important that the edges of grooves 8 and ridges 9of roll 7, illustrated in FIGURES 2 and 4, be rounded off in order toavoid sharp edges. Sharp edges have a tendency to form clean cut paperedges rather than to tear the paper or pull the fibers apart, which isnecessary in practicing this invention.

It has been found, as indicated hereinbefore, that the filter made inaccordance with this invention is more effective in removing tars andother undesirable constituents from tobacco smoke than a filter formedfrom similar paper which has not been torn or pulled apart prior to thegathering and compressing step. For example, a filter made in accordancewith the foregoing embodiment weighing 715 milligrams which has beenembossed and thereafter torn by means of rolls similar to thoseillustrated as 6 and 7 of FIGURE 2 removed about 43% of the tar fromcigarette tobacco smoke. A filter formed from the same type of paperwhich had been embossed but had not been torn removed only 38% of thetars. This filter weighed 780 milligrams. The paper used for form ingeach of these filters weighed 21 grams per square meter, the embossingpressure in each instance was about 63 pounds per nip inch and eachfilter imposed a resistance to the flow of smoke therethrough equal to aloss in head equivalent to a column of water 1.5 inches high at a smokefiow of 17% cc. per second.

Filter tips were also formed from paper containing about 16% charcoal inaccordance with this invention and compared with filters formed fromsimilar paper which had not been torn prior to formation of the filter.In testing these filters it was found that a rod weight of 845 milligrams was sufiicient to impose a resistance to the flow of smoketherethrough equivalent to a loss in head of 1.1 if the paper was tornby means of rolls similar to rolls 6 and 7 of FIGURE 2. On the otherhand, 950 milligrams of paper were required to produce a filter having asimilar resistance if the paper was not torn. Filters made to theseweights were compare for effectiveness and it was found that the lighterweight filter made from paper which had been torn removed 38% of thetars from the tobacco smoke while the heavier filter made from untornpaper removed only 31% of the tars from the tobacco smoke. It isapparent from these results that the filter provided by this inventionis more effective than the heretofore availa ble filters and that thisfilter can be made from less compressible material than is required byfilters made from untorn paper.

FIGURE 10 illustrates a cigarette 24 composed of wrapper 25 and,enclosed within wrapper 25, tobacco 26 and filter 27 formed inaccordance with this invention. Such a filter, provided with rents 28which exposed ragged, fuzzy edges to the tortuous passageways extendinglongitudinally through filter 27, is the type found so effec-' tive inremoving tars from the tobacco smoke as evidenced by the resultspresented hereinbefore.

It is ordinarily important for best results that paper web 1 beconditioned to contain from about 5 to 7% moisture before it isassembled with tobacco to form a cigarette. Tobacco is ordinarilyconditioned to contain about 12% moisture before it is used in makingcigarettes and it has been found that it is necessary that the moisturecontent of the filter rods be within the range specified in order toinsure that the paper will not absorb moisture from the tobacco anddeleteriously affect the smoking quantities of the cigarette. Paperwhich has been impregnated with particles of charcoal in the amount ofsay 15% should be conditioned to contain from 7 to 9% moisture in orderto insure that it will not absorb moisture from the tobacco in thecigarette. As illustrated in FIGURE 1, a convenient method of applyingmoisture to web 1 utilizes an atomizing nozzle 12.

It is preferred that the compressible material utilized as a filler forthe filter of this invention be soft and absorbent paper of the typedisclosed in the copending application of Milton 0. Schur and James C.Rickards, Serial No. 400,072 filed December 23, 1953, of which thisapplication is a continuation-in-part, now United States: Patent2,999,503. This paper is made from high alpha pulp of at least aboutalpha cellulose and weighs. from about 7 to about 30 grams per squaremeter before: creping. The paper is preferably creped. The invention isnot limited to paper meeting these specifications, however, asadvantageous filters may also be formed on the apparatus and inaccordance with the method of this invention from webs or sheets ofsilk, cellulose butyrate acetate and other suitable fibrous filteringmaterial. It has also been found that filters can be formed inaccordance with this invention from paper and other compressiblematerials containing particles of activated charcoal or otherimpregnants and that the tearing operation does not deleteriously affectthe filtering characteristics of the impregnated paper. Indeed, a filterformed from a web of compressible material having particles of activatedcharcoal embedded therein and torn as provided by this invention isadvantageous over filters formed from similar compressible materialwhich was not torn prior to the gathering and compressing step. Theactivated charcoal particles should preferably be combined with thepaper sheet during its formation and should be composed of particleswhich will pass through a Tyler screen having about 100 mesh per linearinch and which will not pass through a Tyler screen having about 300mesh per linear inch. From about 2.5 to about 50% by weight activatedcharcoal can be utilized to advantage but ordinarily not more than aboutto about is required. Although particles of charcoal are exposed at thesurface of the sheet, tearing in accordance with this invention does notmaterially decrease the amount of charcoal in the sheet.

The filtering characteristics of a filter are further improved ifsubstantially unfibrillated paper is utilized in forming the labyrinthalstructure. As is well known in the paper making art, fibrillation is thefirst step in the conversion of pulp into paper. The more the cellulosefibers are fibrillated, that is, the longer they are subjected to theaction of a beater, the greater the surface area of the fibrils and thetighter will be the interlock between the fibrils when they are formedinto a sheet. Paper which has been formed from only moderatelyfibrillated or unfibrillated cellulose has an open structure which issubstantially absorbent and the paper is relatively easily softened,crumpled and torn apart.

Although two types of rolls adapted to tear the web of compressiblematerial in accordance with this invention are illustrated in thedrawing, it is to be understood that many other types of rolls can beutilized to form the rents in the web. Indeed, the paper can be torn byany means in so long as the shreds formed therein have a ragged, fuzzyedge, but it has been found that rolls of the type illustrated in FIGURE2 are particularly well suited for the purpose. The web havingdiscontinuous rents formed by such rolls can be handled on the machinewithout difliculty and can be easily compressed into a filter rod whichcan be wrapped without difficulty. It is to be understood that inpractice the rents may not form any definite pattern in the web but onthe contrary will ordinarily be haphazardly arranged in the webparticularly if. the rents are formed by means of a roll of the typeillustrated in FIGURE 2. The rents may vary in length or diameter, asthe case may be, but as a general rule it is preferred to form a largenumber of rents of small dimension rather than form a smaller number ofrents of larger dimension. Such a practice results in the formation of atorn web which can be more easily handled as a single web than one inwhich the tears or rents are of great dimension. Although rents 10 ofFIGURES 1 and 7 extend longitudinally in the web it is also contemplatedto form laterally extending rents in the web. Such rents may be formedby means of suitable rolls or any other means which will tear or pullapart rather than cut the compressible material. Obviously, such rentswill not extend to the edge of the web.

Although sponge rubber rolls are readily available and admirably suitedfor the purpose, rolls of plastics or other soft materials which areeasily deformed under pressure may be utilized as roll 6 in theembodiment illustrated in the drawing. Likewise, roll 7 can be made fromany one of a variety of materials harder than sponge rubber or othermaterials used for forming roll 6. This roll might be formed from hardplastics for example, or from rubber, brass, aluminum, or any othermetal in which grooves can be formed. Rolls 20 and 21, respectively, maybe made from materials similar to those from which rolls 6 and 7,respectively, are formed, but usually both rolls 20 and- 21 will beformed from a suitable metal.

Because the gathered and compressed fibrous filler material provided bythis invention exerts less pressure against the walls of the wrapper,many types of adhesive can be utilized to securely bind the overlappingedges of the wrapper. For example, paste prepared from casein or starchand water, or a suitable gum adhesive, may be utilized. Use of this typeof torn filler material also permits operation of the forming machine ata greater speed than has heretofore been possible when gathering andcompressing an untorn web of compressible material. Moreover, theproduct has been found to much more uniform in dimensions and inpressure drop.

Although various embodiments of the invention have been described indetail in the foregoing, it is to be understood that such description issolely for the purpose of illustration and that many modifications canbe made by those skilled in the art without departing from the scope andspirit of the invention except as limited by the appended claims.

What is claimed is:

1. In the manufacture of a filter rod from a web of fibrous material,the procedure which consists in longitudinally advancing the web,lacerating the web during its advancement to form haphazard mutilationand fiber displacement without destroying the transverse continuity ofthe web, and converging the lacerated web to form a rod-like bundle.

2. In the manufacture of a filter rod from a web of fibrous material,the procedure which consists in longitudinally advancing the web,lacerating the web during its advancement to form haphazard mutilationand fiber displacement without destroying the transverse continuity ofthe web, converging the lacerated web to form a rod-like bundle, andenclosing the bundle in a tubular wrapper.

3. In the manufacture of a filter rod from a web of fibrous material,the procedure which consists in longitudinally advancing the web,embossing the web during its advancement, thereafter lacerating the webduring its advancement to form haphazard mutilation and fiberdisplacement without destroying the transverse continuity of the web,and converging the lacerated web to form a rod-like bundle.

4. In the manufacture of a filter rod from a web of fibrous material,the procedure which consists in longitudinally advancing the web,successively embossing the web at each surface thereof during itsadvancement and subjecting said web to longitudinal grooving withsimultaneous stretching between a plurality of areas spaced transverselyacross the web to form random elongated discontinuous rents therein, andthereafter converging the embossed and grooved web to form a rod-likebundle.

5. In the manufacture of a filter rod from a web of fibrous material,the procedure which consists in longitudinally advancing the web,passing the said web during its advancement between opposed groovingrolls having a plurality of interfitting grooves and ridges, therebyforcing said web into said grooves and stretching said web laterallybeyond its elastic limit to form random elongated discontinuous rentstherein, and thereafter converging the grooved web to form a rod-likebundle.

6. In an apparatus of the character described, means for feeding a webof paper, mutilating means operative upon the web to displace anddisarrange the fibers of the paper, means by which the web is convergedinto rod-like formation and enclosed in a tubular wrapper, and meansbetween the mutilating means and the wrapper-enclosing means fortensioning the paper to an extent beyond the limits of its elasticity.

7. In an apparatus of the character described, means for feeding afibrous web, a web-mutilating apparatus through which the web is movedand which lacerates the web to release fibers thereof without destroyingthe transverse continuity of the web, means for compacting the mutilatedweb, means for applying a wrapper around the compacted web to form afilter rod, tensioning means in- 7 dependent of the web-feeding meansand interposed between the web-feeding means and the wrapper applyingmeans for stretching the compacted web as it approaches the wrapperapplying means, and means for severing the filter rod into predeterminedlengths.

8. In an apparatus of the character described, means for advancing afibrous Web, means for embossing said web during its advancement, meansby which the web is converged into rod-like formation, and groovingmeans between the embossing means and the converging means comprisingopposed rolls having a plurality of interfitting circumferential groovesand ridges for stretching the Web laterally to an extent beyond thelimits of its elasticity.

9. In an apparatus of the character described, means for advancing afibrous web, means for embossing said web during its advancement, meansby which the web is converged into rod-like formation, and groovingmeans between the embossing means and the converging means, saidgrooving means comprising a pair of opposed rolls, one having a softdeformable surface and the other having a hard surface provided with aplurality of circumferential grooves and ridges, thereby forcing saidweb during its advancement into said grooves and simultaneously groovingsaid Web and stretching it laterally to produce disconnected rentstherein.

10. In an apparatus of the character described, means for advancing afibrous Web, means for embossing said web during its advancement, meansby which the web is converged into rod-like formation, and groovingmeans between the embossing means and the converging means, saidembossing means comprising a pair of opposed rolls, one of said rollshaving a roughened surface and the other having a smooth surface forcingthe web during its advancement against the said roughened roll surface.

No references cited.

FRANK E. BAILEY, Primary Examiner. B. STICKNEY, Examiner.

Disclaimer 3,238,852.-]l[i?t0n Oscar Schur, Asheville, and JamesRichards, Brevard, N.C. METHOD AND APPARATUS FOR MAKING FILTERS. Patent,dated Mar. 8, 1966. Disclaimer filed Aug 10, 1970, by the assignee, OlinCorporation. Hereby enters this disclaimer to claims 5, 8 and 10 of saidpatent.

w n-m Gazette January 26', I971]

1. IN THE MANUFACTURE OF A FILTER ROD FROM A WEB OF FIBROUS MATERIAL,THE PROCEDURE WHICH CONSISTS IN LONGITUDINALLY ADVANCING THE WEB,LACERATING THE WEB DURING ITS ADVANCEMENT TO FORM HAPHAZARD MUTILATIONAND FIBER DISPLACEMENT WITHOUT DESTROYING THE TRANSVERSE CONTINUITY OFTHE WEB, AND CONVERGING THE LACERATED WEB TO FORM A ROD-LIKE BUNDLE.